The field of the present invention is heating systems for building.
Recent trends in innovative heating for buildings have turned to low temperature systems capable of accommodating such heat sources as solar energy. A major difficulty remaining with such systems is that the initial investment for solar energy equipment as well as the more conventional backup fossil fuel heaters and the like detracts from the advantages of such systems. Consequently, it has been a goal of the progressive alternative energy industry to control initial investment costs and to increase the efficiency of such systems to reduce the required fossil fuel usage.
A space heating system designed with these goals in mind is disclosed in U.S. Pat. Nos. 3,526,361, 3,655,127, 3,844,687 and 3,926,537, to Piper, the disclosures of which are incorporated herein by reference. These earlier systems incorporate frame members of a structure to form conduits through which air is forced by means of a blower. Positioned across the conduit is a heat exchange coil designed to accommodate hot water below the boiling range. Air is drawn in from the space to be heated by the blower, passed through the heat exchange coil and returned to the space. For a building with several rooms, several units, each with its blower and coil were proposed.
In an attempt to reduce initial investment by avoiding the need for conduit, heating systems have attempted to employ the heating of a plenum above or below the occupied space of a building. This plenum is in communication with the various rooms of the building by means of vents through which gravity flow of the heated air could pass. This system significantly reduces the initial investment by removing the cost of the heater conduits. However, it then becomes necessary to heat an additional large space.
To reduce the demand on heating systems, insulation has been employed in ceilings and walls. In homes not built on slabs, insulation has also been found beneficial beneath floors because of the requirement that the crawl space beneath such buildings be vented. As crawl spaces must be vented, they are generally found to be at or near the outside ambient temperature. It is for this reason that such insulation under the floor has been required in areas experiencing extreme cold during periods of the year.